hmm...i don't see how that could be right...i have a slightly different processor (E6400) and my temps idle before OCing were around 30 and 40 at load.
i have 2 120mm fans and a 250mm intake fan so i probably have you beat on cooling too so i really don't see how your temps could be so much lower.
I'd say if you want to know what you idle temps are then go into BIOS and look there. most motherboards have a temp monitoring dealio in BIOS so that'd probably have it in there and it should be more accurate than about anything else you could use.
Antec NeoPower 650W
Intel Core 2 Duo E8400 (w/ Arctic Freezer 7)
4GB DDR2-1000 G.Skill
Sapphire x1950 Pro 512mb (w/ V700)
250GB, 500GB and 1.5TB Seagate Barracudas (2.25TB total)
Fatal1ty XtremeGamer sound card *** generic TV tuner
Xclio 3060 case *** HannsG 22" monitor
XP Pro / Ubuntu 7.10 *** Razer Copperhead and Tarantula